1. Field of the Invention
The present invention relates generally to the fields of endocrinology, stem cells, and differentiated cells. More particularly, it concerns the production of self-renewing endoderm progenitor cells from undifferentiated cells in a suspension culture.
2. Description of Related Art
Endoderm-derived tissues, including pancreas, are potentially useful for cell replacement therapies. It is possible to generate definitive endoderm, which forms the primitive gut tube during development, and its derivative lineages from pluripotent stem cells (PSCs) in vitro through sequential exposure to cytokines that mimic embryonic morphogenesis. In this fashion, pancreatic cells can be produced from embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) (D'Amour et al., 2006; Gouon-Evans et al., 2006). While these studies highlight the promise of PSC-derived endodermal tissues for transplantation therapies, several obstacles remain. Endodermal cells generated from PSCs tend to display immature phenotypes and in many instances are not fully functional. For example, most pancreatic beta cells currently generated in vitro from human ESCs are poly-hormonal and not glucose responsive (D'Amour et al., 2006; Nostro et al., 2011). An additional obstacle in the production of endodermal cells for use in transplantation is the ability to scale the production to produce the required number of cells, which for pancreatic cells is currently limited by the necessity for production on a solid surface. It is an objective of the present invention to provide culture and isolation methods that avoid these limitations.